It is often desirable to cut openings in walls, especially those made of concrete, reinforced and otherwise, stone, and other hard materials. One method of cutting such openings utilizes a circular saw assembly which is guided along a track, the track being attached to the surface being cut. A circular blade of diamond-impregnated or other hardened material is turned at a high rate of speed to cut a kerf or cutting line along a desired surface. A variety of methods are used to move the saw assembly along the track.
Methods and apparatus for cutting openings in concrete walls and other similar surfaces are described in U.S. Pat. Nos. 3,763,845 and 3,722,497. These two patents illustrate circular saw assemblies which are mounted on a guide track attached to the surface being cut, and moved along the guide track by means of a gear-driving device. The guide track is laid along a plane parallel to a desired cutting plane. The blade of the circular saw assembly, extending laterally outward and parallel to the track, is then utilized to cut a channel or kerf along a desired cutting plane to a point which is perpendicular to another proposed kerf. Since most openings are rectangular or square in nature, this cutting procedure is accomplished four times prior to removal of the block defined by the four kerfs. The '845 patent also illustrates a particularly useful track structure and trolley for mounting the circular saw assembly to the track.
The problem with utilizing a circular cutting saw to cut the four kerfs, is that, due to the nature of the circular saw blade, a square cut cannot be produced. The circular saw, having a round cutting blade, produces a cut having ends which are not square to the surface of the wall, i.e., do not extend uniformly through the thickness of the wall in a direction perpendicular to the wall surface. In order to remove the slab of concrete from the wall, it is currently necessary to overcut corners on the front surface of the wall so that the arc of the circular blade intersects with the arc of the adjoining cut at the rear portion of the wall. Such overcuts produce stress concentration points, which can lead to cracking of the wall in that area. The overcuts must also be filled for aesthetic purposes, thus requiring additional manpower and materials.
One procedure for producing openings in concrete without overcuts is to use a core drill at the corners to remove material remaining in the kerf. Core drilling is time consuming, however, and openings made in this way still require patching at the corners.
Thus, it is desirable to provide an easier, quicker and more effective procedure and apparatus for producing openings in concrete walls without overcuts or core-drilled corners.
It is another feature of the present invention to provide an apparatus that can be used with trackmounted circular saw assemblies to provide essentially square corner cuts.
It is yet another feature of the present invention to provide an apparatus capable of cutting a kerf along a wall at a point flush with a ceiling, floor or second wall.